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Despite three decades of political efforts and a wealth of research on the causes and catastrophic impacts of climate change, global carbon dioxide emissions have continued to rise and are 60% higher today than they were in 1990. Exploring this rise through nine thematic lenses—covering issues of climate governance, the fossil fuel industry, geopolitics, economics, mitigation modeling, energy systems, inequity, lifestyles, and social imaginaries—draws out multifaceted reasons for our collective failure to bend the global emissions curve. However, a common thread that emerges across the reviewed literature is the central role of power, manifest in many forms, from a dogmatic political-economic hegemony and influential vested interests to narrow techno-economic mindsets and ideologies of control. Synthesizing the various impediments to mitigation reveals how delivering on the commitments enshrined in the Paris Agreement now requires an urgent and unprecedented transformation away from today's carbon- and energy-intensive development paradigm.

To respond to the climate crisis, we need to accelerate system transformations at a pace, scale, and breadth not seen before. This means that it is urgent to shift development pathways towards net zero greenhouse gas emissions, even while progressing towards other sustainable development objectives. This paper argues that accelerated mitigation can not only benefit from policies that are outside the domain of conventional emission-focused mitigation policies but require such policies. We refer to this process as shifting development pathways towards sustainability. Here, we explore what enabling conditions make such shifts possible. We develop a framework to select examples of shifts — in realms such as educational access, housing access, fiscal arrangements, and institutional reform. We analyse them against key enablers. Our findings suggest that countries could learn from what has worked elsewhere, though context matters. Some enablers are more widely applicable, including finance, long-term vision, and focus on sustainable development objectives. Multiple enablers, integrated policy packages, and involvement of a broad range of actors help achieve multiple objectives. Some enablers may yield results in the near term, while others take time to yield results. Based on our analysis, we suggest that climate mitigation requires an “all of economy, all of society” approach. Graphical Abstract

This report aims to gauge France'sfair share of the global response to the climate emergency, starting from the recognition that equity is important – in fact, necessary – for addressing climate change. In the first instance, the report focuses on mitigation, but acknowledges that an equitable approach to adaptation, loss and damage, just transitions and so forth is of course equally important. To that end, it also calculates whatfraction of the global climate finance need could be argued to be France's fair share and provides an approach, and results, to gauge the amount of finances that would be required to fulfill this fair share. Overall, the reportuses a flexible and transparent framework for equitable effort sharing that is drawn directly from the core equity principles of the United Nations Framework Convention on Climate Change (UNFCCC).The analysis is done using theClimate Equity Reference Calculator, an online tool and database that allows users to select specific equity-related settings relating to responsibility, capacity and other key parameters, and then to use straightforward, standard quantitative indicators to calculate the implied national fair shares of the global mitigation effort. The analysis is based on a specific input selectioninformed by ethical and empirical considerations that are discussed in more detail within the report (results for sensitivity cases with different ethical considerations are also discussed). This approach allows the report to contrast the mitigationtarget and climate finance pledgesadopted by France with its fair share, and to articulate what France should do in addition to its existing pledge to be in line with its moral obligations. Cerapport est disponible en français aussi:https://doi.org/10.5281/zenodo.2595500

Severe climate-related disasters have already disproportionately affected some of the world’s most vulnerable countries, which are typically some of the least-responsible for the catastrophes. This report highlights the stalemate of international loss and damage support and what can be done to shore up higher-income countries’ responsibilities – starting with COP26.

There is increasing interest in cross-scale scenario development, driven in part by developments in climate scenarios. Climate mitigation and adaptation studies have long emphasized the link between global change and local action, and recent climate community scenarios have been developed with cross-scale application in mind. Conceptually, global scenarios have been proposed as ‘boundary conditions’ on regional and local scenarios. However, while the concept is compelling, to date we have found only one formal proposal (by Schweizer and Kurniawan) of what it might mean from a scenario development perspective. That proposal used cross-impact balances (CIB), which offer a promising route to formalization of cross-scale scenario analysis. In this paper we also apply CIB, but allow for weak, rather than zero, cross-scale interactions. We formalize the concept of weak interactions by extending CIB analysis to allow for metastable states, which are stable under small disturbances. We propose an algorithm for identifying metastable states and for combining states that become connected when small disturbances are present. Arguing that large-scale scenarios can be applied as boundary conditions when they are metastable under the influence of processes at smaller scales, we demonstrate how a simplified CIB can replace a full multi-scale CIB when a metastable scenario kernel is adopted at large scale.

The Parties to the UNFCCC and Paris Agreement agreed to act on the basis of equity to protect the climate system. Equitable effort sharing is an irreducibly normative matter, yet some influential studies have sought to create quantitative indicators of equitable effort that claim to be value-neutral (despite evident biases). Many of these studies fail to clarify the ethical principles underlying their indicators, some mislabel approaches that favour wealthy nations as ‘equity approaches’ and some combine contradictory indicators into composites we call derivative benchmarks. This Perspective reviews influential climate effort-sharing assessments and presents guidelines for developing and adjudicating policy-relevant (but not ethically neutral) equity research. Contributions to mitigate climate change should be equitable under the Paris Agreement, yet researchers take sharply diverging approaches to assessing national effort. This Perspective evaluates the literature and presents guidelines for policy-relevant—and ethically explicit—research on equity.

In the 25 years from 1990 to 2015, annual global carbon emissions grew by 60%, approximately doubling total global cumulative emissions. This has brought the world perilously close to exceeding 2°C of warming, and it is now on the verge of exceeding 1.5°C. This paper examines the starkly different contributions of different income groups to carbon emissions in this period. It draws on new data that provides much improved insight into global and national income inequality, combined with national consumption emissions over this 25-year period, to provide an analysis relating emissions to income levels for the populations of 117 countries. Future scenarios of carbon inequality are also presented based on different possible trajectories of economic growth and carbon emissions, highlighting the challenge of ensuring a more equitable distribution of the remaining and rapidly diminishing global carbon budget.

Carbon emissions—and hence fossil fuel combustion—must decline rapidly if warming is to be held below 1.5 or 2 °C. Yet fossil fuels are so deeply entrenched in the broader economy that a rapid transition poses the challenge of significant transitional disruption. Fossil fuels must be phased out even as access to energy services for basic needs and for economic development expands, particularly in developing countries. Nations, communities, and workers that are economically dependent on fossil fuel extraction will need to find a new foundation for livelihoods and revenue. These challenges are surmountable. In principle, societies could undertake a decarbonization transition in which they anticipate the transitional disruption, and cooperate and contribute fairly to minimize and alleviate it. Indeed, if societies do not work to avoid that disruption, a decarbonization transition may not be possible at all. Too many people may conclude they will suffer undue hardship, and thus undermine the political consensus required to undertake an ambitious transition. The principles and framework laid out here are offered as a contribution to understanding the nature of the potential impacts of a transition, principles for equitably sharing the costs of avoiding them, and guidance for prioritizing which fossil resources can still be extracted.

This paper focuses on the risks associated with “negative emissions” technologies (NETs) for drawing carbon dioxide from the atmosphere through photosynthesis and storing it in land-based sinks or underground. Modelled mitigation pathways for 1.5 °C assume NETs that range as high as 1000 Gt CO2. We argue that this is two to three times greater than the amount of land-based NETs that can be realistically assumed, given critical social objectives and ecological constraints. Embarking on a pathway that assumes unrealistically large amounts of future NETs could lead society to set near-term targets that are too lenient and thus greatly overshoot the carbon budget, without a way to undo the damage. Pathways consistent with 1.5 °C that rely on smaller amounts of NETs, however, could prove viable. This paper presents a framework for assessing the risks associated with negative emissions in the context of equity and sustainable development. To do this, we identify three types of risks in counting on NETs: (1) that NETs will not ultimately prove feasible; (2) that their large-scale deployment involves unacceptable ecological and social impacts; and (3) that NETs prove less effective than hoped, due to irreversible climate impacts, or reversal of stored carbon. We highlight the technical issues that need to be resolved and—more importantly—the value judgements that need to be made, to identify the realistic potential for land-based NETs consistent with social and environmental goals. Given the critical normative issues at stake, these are decisions that should be made within an open, transparent, democratic process. As input, we offer here an indicative assessment of the realistic potential for land-based NETs, based on a precautionary assessment of the risks to their future effectiveness and a provisional assessment of the extent to which they are in conflict with sustainable development goals related to land, food and climate.

The problem of fairly distributing the global mitigation effort is particularly important for the 1.5 °C temperature limitation objective, due to its rapidly depleting global carbon budget. Here, we present methodology and results of the first study examining national mitigation pledges presented at the 2015 Paris climate summit, relative to equity benchmarks and 1.5 °C-compliant global mitigation. Uniquely, pertinent ethical choices were made via deliberative processes of civil society organizations, resulting in an agreed range of effort-sharing parameters. Based on this, we quantified each country’s range of fair shares of 1.5 °C-compliant mitigation, using the Climate Equity Reference Project’s allocation framework. Contrasting this with national 2025/2030 mitigation pledges reveals a large global mitigation gap, within which wealthier countries’ mitigation pledges fall far short, while poorer countries’ pledges, collectively, meet their fair share. We also present results for individual countries (e.g. China exceeding; India meeting; EU, USA, Japan, and Brazil falling short). We outline ethical considerations and choices arising when deliberating fair effort sharing and discuss the importance of separating this choice making from the scholarly work of quantitative “equity modelling” itself. Second, we elaborate our approach for quantifying countries’ fair shares of a global mitigation effort, the Climate Equity Reference Framework. Third, we present and discuss the results of this analysis with emphasis on the role of mitigation support. In concluding, we identify twofold obligations for all countries in a justice-centred implementation of 1.5 °C-compliant mitigation: (1) unsupported domestic reductions and (2) engagement in deep international mitigation cooperation, through provision of international financial and other support, or through undertaking additional supported mitigation activities. Consequently, an equitable pathway to 1.5 °C can only be imagined with such large-scale international cooperation and support; otherwise, 1.5 °C-compliant mitigation will remain out of reach, impose undue suffering on the world’s poorest, or both.

Equity issues have long been debated within international climate politics, focused on fairly distributing reductions in territorial emissions and fossil fuel consumption. There is a growing recognition among scholars and policymakers that curbing fossil fuel supply (as well as demand) can be a valuable part of the climate policy toolbox; this raises the question of where and how the tool should be applied. This paper explores how to equitably manage the social dimensions of a rapid transition away from fossil fuel extraction. Fossil fuel extraction leads to benefits for some people (such as extraction workers) and harms for others (such as pollution-affected communities). A transition must respect and uphold the rights of both groups, while also staying within climate limits, as climate impacts will fall most heavily on the world’s poor. This paper begins by reviewing how extraction affects economies and communities and the different transitional challenges they face. Based on that review, it then examines three common equity approaches – economic efficiency, meeting development needs, and effort-sharing. Drawing lessons from the strengths and weaknesses of these approaches, the paper proposes five principles as a basis for equitably curbing fossil fuel extraction within climate limits: (1) Phase out global extraction at pace consistent with limiting warming to 1.5°C; (2) Enable a just transition for workers and communities; (3) Curb extraction consistent with environmental justice; (4) Reduce extraction fastest where doing so will have the least social costs; (5) Share transition costs fairly, according to ability to bear those costs. Key policy insights:Fossil fuel extraction is unlikely to be a viable path to development because the Paris Agreement goals require most fossil fuel use to be ended within a generation;Extraction should be phased out fastest in diversified, wealthier economies that can better absorb the transitional impacts;Governments of extracting countries should enact ambitious industrial policy to diversify their economies, alongside economic and employment policies to enable a just transition;The costs of a just transition should be borne by those most able to bear it: poorer countries can reasonably demand financial support. Fossil fuel extraction is unlikely to be a viable path to development because the Paris Agreement goals require most fossil fuel use to be ended within a generation; Extraction should be phased out fastest in diversified, wealthier economies that can better absorb the transitional impacts; Governments of extracting countries should enact ambitious industrial policy to diversify their economies, alongside economic and employment policies to enable a just transition; The costs of a just transition should be borne by those most able to bear it: poorer countries can reasonably demand financial support.

Journal article describing the functionality of cerc-web, the Climate Equity Reference Calculator web interface. The main installation of cerc-web is found at http://calculator.climateequityreference.org/ and the source code can be viewed at http://github.com/climateequityreferenceproject/cerc-web/

This report aims to gauge Norway’s fair share of the global response to the climate problem, starting from the recognition that equity is important – in fact, necessary – for addressing climate change. The report focuses on mitigation, although an equitable approach to adaptation is of course equally important. It uses a flexible and transparent framework for equitable effort sharing that is drawn directly from the core equity principles of the United Nations Framework Convention on Climate Change (UNFCCC). The analysis is done using the Climate Equity Reference Calculator, an online tool and database that allows users to select specific equity-related settings relating to responsibility, capacity and other key parameters, and then to use straightforward, standard quantitative indicators to calculate the implied national fair shares of the global mitigation effort. The analysis is based on a range of alternative input selections informed by ethical and empirical considerations that are discussed in more detail within the report. This approach allows the report to contrast Norway's pledged contribution towards the Paris Agreement goals with its fair share, and to articulate what Norway should do in addition to its existing pledge to be in line with its moral obligations.

The recent article by Robiou du Pont et al makes counter-intuitive claims about the degree to which different countries’ pledged mitigation contributions under the Paris Agreement are “equitable”, i.e., whether they meet benchmarks associate with various equity approaches. The analysis is flawed however, in three ways, with a cascading and systematic bias against poorer and lower-emitting countries. Firstly, the methodology is heavily driven by “grandfathering” as an allocation approach, despite the absence of any ethical justification. Second, it omits “Responsibility” as a basis, without explanation, even though it is included in the set of categories (taken from the IPCC AR5) within which the authors claim to be working. And third, the IPCC raised several other ethical considerations not covered by the authors’ particular choice of categories. Each of these three analytical shortcomings biases the results in favor of the wealthier and higher-emitting countries.

The article Whose carbon is burnable? Equity considerations in the allocation of a “right to extract,” written by Sivan Kartha, Simon Caney, Navroz K. Dubash, and Greg Muttitt, was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 24 May 2018.

The urgency of the climate problem seems to require that stringent emissions reductions begin under the political economic institutions that currently exist. Any global climate treaty must, however, at least not make global inequality worse, and ideally should embody desirable principles of justice. The Greenhouse Development Rights framework (GDRs), described briefly here, is a proposal for such a fair division of the burdens of emissions reductions and adaptation to climate change that won't be avoided, based on an assessment of capacity (ability to pay) and responsibility (contribution to the problem). The GDRs considers both inequality within countries and inequality between countries: national obligations are based on the exemption of poor individuals (under a ‘development threshold’) from global burdens. GDRs accepts the link between ‘development’ and the growth in consumption of the world's poor majority, an obvious requirement if it is to be taken seriously by Southern governments intent on ‘development as usual’. It also does not directly challenge the institutions of capitalism or the sovereignty of nation states. Nonetheless, in its focus on poor and rich people it is consistent with a class-based rather than nation-based approach to economic justice. We conclude by raising a variety of questions both about the limits of approaches like GDRs, and the need for policies that address climate change even during or after a transition beyond the current global capitalist regime.

Good climate policy requires the best possible understanding of how climatic change will impact on human lives and livelihoods in both industrialized and developing counties. Our review of recent contributions to the climate-economics literature assesses 30 existing integrated assessment models in four key areas: the connection between model structure and the type of results produced; uncertainty in climate outcomes and projection of future damages; equity across time and space; and abatement costs and the endogeneity of technological change. Differences in treatment of these issues are substantial and directly affect model results and their implied policy prescriptions. Much can be learned about climate economics and modelling technique from the best practices in these areas; there is unfortunately no existing model that incorporates the best practices on all or most of the questions we examine.

The vast majority of emission reductions required to prevent dangerous climate change must be made in the developing world. Yet the human development aspirations of developing countries requires expanded energy services, which has historically always been accompanied by rising carbon emissions. Developing countries have thus firmly asserted that a solution to climate change cannot come at the expense of their development. The Greenhouse Development Rights (GDR) framework is a climate regime architecture explicitly structured to safeguard a right to development, and thus make an ambitious global solution possible. It is a burden-sharing framework that defines national obligations, based on responsibility for the climate change problem and capacity to solve it. Both are defined with respect to a “development threshold” that serves to relieve from the costs and constraints of the climate crisis those individuals still striving for a decent standard of welfare. Highlighting the United States and China, we dis...

Hydrogen is an energy carrier able to be produced from domestic, zero-carbon sources and consumed by zero-pollution devices. A transition to a hydrogen-based economy could therefore potentially respond to climate, air quality, and energy security concerns. In a hydrogen economy, both mobile and stationary energy needs could be met through the reaction of hydrogen (H2) with oxygen (O2). This study applies a full fuel cycle approach to quantify the energy, greenhouse gas emissions (GHGs), and cost implications associated with a large transition to hydrogen in the United States. It explores a national and four metropolitan area transitions in two contrasting policy contexts: a "business-as-usual" (BAU) context with continued reliance on fossil fuels, and a "GHG-constrained" context with policies aimed at reducing greenhouse gas emissions. A transition in either policy context faces serious challenges, foremost among them from the highly inertial investments over the past century or so in technology and infrastructure based on petroleum, natural gas, and coal. A hydrogen transition in the USA could contribute to an effective response to climate change by helping to achieve deep reductions in GHG emissions by mid-century across all sectors of the economy; however, these reductions depend on the use of hydrogen to exploit clean, zero-carbon energy supply options. � 2008 Elsevier Ltd. All rights reserved.

The assignment of obligations to pay for mitigation of greenhouse gas emissions and for adaptation to unavoidable climate change is a critical and controversial component of international negotiations under the United Nations Framework Convention on Climate Change. In this article we present a new framework called ‘Greenhouse Development Rights’ (GDRs): a formula for the calculation of national obligations on the basis of quantified capacity (wealth) and responsibility (contribution to climate change). GDRs seek to preserve the ‘right to development’ by exempting from obligation any income and emissions under a ‘development threshold’. By taking into account the distribution of income and emissions within countries, and calculating national obligations as if they were the aggregated obligations of individuals, the framework treats every global citizen identically, and allocates obligations even to poor countries that are proportional to their actual middle-class and wealthy populations. When coupled to a ...

Traditional biomass remains the dominant contributor to the energy supply of a large number of developing countries, where it serves the household energy needs of over a third of humanity in traditional cookstoves or open fires. Efforts to reduce the enormous human health, socioeconomic, and environmental impacts by shifting to cleaner cookstoves and cleaner biomass-derived fuels have had some success, but much more needs to be done, possibly including the expanded use of fossil-derived fuels. Concurrently, biomass is rapidly expanding as a commercial energy source, especially for transport fuels. Bioenergy can positively contribute to climate goals and rural livelihoods; however, if not implemented carefully, it could exacerbate degradation of land, water bodies, and ecosystems; reduce food security; and increase greenhouse gas (GHG) emissions. For large-scale commercial biofuels to contribute to sustainable development will require agriculturally sustainable methods and markets that provide enhanced livelihood opportunities and equitable terms of trade. The challenge lies in translating the opportunity into reality.

In the long term, any definition of adequacy consistent with UNFCCC Article 2 will require increased mitigation efforts from almost all countries. Therefore, an expansion of emission limitation commitments will form a central element of any future architecture of the climate regime. This expansion has two elements: deepening of quantitative commitments for Annex B countries and the adoption of commitments for those countries outside of the current limitation regime. This article seeks to provide a more analytical basis for further differentiation among non-Annex I countries. To be both fair and reflective of national circumstances, it is based on the criteria of responsibility, capability and potential to mitigate. Altogether, non-Annex I countries were differentiated in four groups, each including countries with similar national circumstances: newly industrialized countries (NICs), rapidly industrializing countries (RIDCs), ‘other developing countries’, and least developed countries (LDCs). Base...

Project-based emission reduction or ‘offset’ programs are being implemented widely, from the CDM (Clean Development Mechanism) to corporate voluntary efforts and municipal and state-level activities. Additionality assessment remains a central and persistent challenge in all programs. Concerns have been raised with methods currently used, such as investment analysis, barrier analysis, and performance thresholds. They have been variously critiqued for high costs, resistance to standardization, weak environmental integrity, and susceptibility to gaming. Technology penetration rates provide another means to infer additionality, and could be a potentially useful complement to other methods. The notion is that emerging technologies with low but increasing penetration rates typically require some type of support, as might be provided through offsets markets, to compete effectively in the marketplace. For penetration rate analysis to provide a useful tool for additionality assessment, several fundamental...

The success of the Clean Development Mechanism (CDM) and other credit-based emission trading regimes depends on effective methodologies for quantifying a project's emissions reductions. The key methodological challenge lies in estimating project's counterfactual emission baseline, through balancing the need for accuracy, transparency, and practicality. Baseline standardisation (e.g. methodology, parameters and/or emission rate) can be a means to achieve these goals. This paper compares specific options for developing standardised baselines for the electricity sector—a natural starting point for baseline standardisation given the magnitude of the emissions reductions opportunities. The authors review fundamental assumptions that baseline studies have made with respect to estimating the generation sources avoided by CDM or other emission-reducing projects. Typically, studies have assumed that such projects affect either the operation of existing power plants (the operating margin) or the construction of new generation facilities (the build margin). The authors show that both effects are important to consider and thus recommend a combined margin approach for most projects, based on grid-specific data. They propose a three-category framework, according to projects’ relative scale and environmental risk.

This article provides a first-cut estimate of the potential impacts of the clean development mechanism (CDM) on electricity generation and carbon emissions in the power sector of non-Annex 1 countries. We construct four illustrative CDM regimes that represent a range of approaches under consideration within the climate community. We examine the impact of these CDM regimes on investments in new generation, under illustrative carbon trading prices of US$ 10 and 100/t C. In the cases that are most conducive to CDM activity, roughly 94% of new generation investments remains identical to the without-CDM situation, with only 6% shifting from higher to lower carbon intensity technologies.We estimate that the CDM would bolster renewable energy generation by as little as 15% at US$ 10/t C, or as much as 300% at US$ 100/t C. A striking finding comes from our examination of the potential magnitude of the “free-rider” problem, i.e. crediting of activities that will occur even in the absence of the CDM. The C...

Biomass energy can be “modernized” worldwide, i.e., produced and used much more efficiently and cost-competitively, generally in the more convenient forms of gases, liquids, or electricity. This article is a summary of a recently published book whose objective is to provide information to help expand the contributions that modernized biomass energy makes to sustainable development in developing countries. The article discusses the present and possible future magnitude of bioenergy contributions to global energy supply, efficiency gains that are possible by modernization of bioenergy, alternative sources of biomass for energy, a variety of socioeconomic and environmental issues that can arise with the production and use of bioenergy, and institutions and institutional mechanisms that would facilitate a greater role for modernized biomass energy.

Defying the conventional wisdom regarding first-order transitions, {ital solid{minus}solid} {ital displacive} {ital transformations} are often accompanied by pronounced pretransitional phenomena. Generally, these phenomena are indicative of some mesoscopic lattice deformation that ``anticipates`` the upcoming phase transition. Among these precursive effects is the observation of the so-called ``tweed`` pattern in transmission electron microscopy in a wide variety of materials. We have investigated the tweed deformation in a two-dimensional model system, and found that it arises because the compositional disorder intrinsic to any alloy conspires with the natural geometric constraints of the lattice to produce a frustrated, glassy phase. The predicted phase diagram and glassy behavior have been verified by numerical simulations, and diffraction patterns of simulated systems are found to compare well with experimental data. Analytically comparing to alternative models of strain-disorder coupling, we show that the present model best accounts for experimental observations.

Fossil fuel combustion, the technology on which the world relies most heavily for power generation, heating and transportation, was adopted long before its environmental burdens had been fully recognized. The results of our recent efforts to mitigate these environmental costs are perceptible, but still modest and very costly. Despite the use of sulfur scrubbers, acid rain remains a serious regional threat, especially with the increased use of lowquality coals. Catalytic converters have reduced nitrogen oxide and carbon monoxide emissions from automobiles in some countries, but the poor air quality of many of the world's urban areas nonetheless constitutes a severe health threat. New, more efficient power plants and automobiles generate less carbon dioxide per unit of useful energy than did their predecessors, but atmospheric carbon dioxide concentrations continue to rise, intensifying the threat of global warming. Despite our diligent efforts, a major strategic shift in energy production may be required t...

What is the appropriate balance between scientific analysis and governmental input in the IPCC? Claiming government overreach and calling for greater insulation of the process come from a misleadingly simple interpretation. Such insulation would likely diminish the policy relevance of the SPM. The SPM is “approved” by governments, not merely “accepted” as is the main report, which invests it with an important measure of governmental ownership. An approval process is worth preserving, as it is precisely what makes the IPCC distinct from any number of technical reports. We explore an alternative vision for articulating science and politics at the IPCC. ![Figure][1] Anthropogenic GHG emissions, by country income group: Over recent decades, emissions from different groups have displayed markedly different patterns. Groups based on World Bank 2013 country income classification. ( A ) Annual total emissions. \[Reproduced from figures TS.4 and 1.4 (1)\] ( B ) Distribution of annual per capita emissions. \[Reproduced from figures TS.4, 1.8c, and 5.19 (1)]. ( C ) Annual median per capita emissions. [Modified from figures TS.4 and 1.4 (1)\] ( D ) Annual median emissions per unit of gross domestic product. GDP expressed in 2005 international dollars. [Computed from economic data in figure 5.15 using country income groupings and emissions reported in chart 2 (1)] As the parties work toward a next phase in the global climate treaty to be agreed on in late 2015, perhaps the single most contentious issue is that of country groupings, as they are directly linked to national commitments under the UNFCCC. IPCC findings perceived to influence revision of groupings were thus liable to trigger a confrontation in Berlin. As income growth has been identified as a key driver of emissions growth, income groups appear a natural analytical tool, although the full WGIII report most frequently uses traditional regional groups, as well as sectoral disaggregation. At least two challenges confront any grouping approach in the context of an SPM. First, in the negotiation context, analytical groupings are inevitably interpreted as to implications for political groupings. Imposing political perceptions in the context of a scientific assessment might be seen as intrusive. However, in producing an SPM with explicit government buy-in, engagement on such issues is inevitable. The question is how to make it productive. Second, grouping heterogeneous and rapidly changing countries into a few categories necessarily elides relevant information. Country groups contain large variances (chart 2B), aggregate statistics can be dominated by a few countries, and many alternative groupings are possible. Small changes in number of groups, thresholds between groups, types of characteristics, and reference period can lead to large changes in findings with substantial political implications. For example, chart 2 categorizes countries according to their current (2013) income, showing that UMCs accounted for three-quarters of global emissions rise from 2000 to 2010. A political interpretation of this may be that the UNFCCC must update its country groupings to reflect the role of UMCs and to impose commensurate emission limits. However, the same representation based on countries' income in a year during the 2000–2010 decade (e.g., 2005) would show that three-quarters of the 2000–2010 global emissions rise arose in lower-middle-income countries, rather than UMCs, and a further 20% in low-income countries. A corresponding political interpretation might stress the need for financial and technological support to enable countries to develop along a lower-carbon pathway through low- and lower-middle income stages. The two representations would be equally faithful to underlying data, but also equally synthetic and incomplete, and differ markedly in the political extrapolations to which they ostensibly lend credence. ![][2] Land use, like deforestation in Indonesia, drives emissions in lower-income countries. PHOTO: JOHN VAN HASSELT/CORBIS What happened with two other sections of the SPM suggests that the outcome of political debate on scientific findings is contingent. The framing section of the SPM deals with very contentious issues about the need for cooperation in mitigation and technology, as well as the centrality of equity in burden-sharing and in the evaluation of costs and benefits, among others. Yet, agreement was reached on this section—indeed, it was expanded rather than truncated. This was due, in part, to serendipity; the framing section was taken up for discussion early in the approval process, which allowed 4 days for discussion and iterations of text, and that enabled convergence on what authors sought to convey and the political-legal sensibilities brought by country delegates. In contrast, discussion of another section, on international cooperation, produced much shorter text and simplified content, stripped of controversial elements. This was due both to the short time available for this discussion and to a general spirit of contention after the removal of several figures. What does this suggest about the IPCC process? The main IPCC report should be focused on establishing and presenting scientific facts. But seemingly technical choices can crystallize into value-laden political conclusions, particularly given tight word and time limits. It is more productive for authors to be aware of alternative political interpretations of their concepts and findings and to factor these into representations of data, than to strive, unrealistically, to ignore political concerns. This requires rethinking the SPM as a coproduction process in which salient political discussions are connected to relevant scientific material. Changes in the SPM writing process can help: creating more channels and space for dialogue before the pressure cooker of a time-limited approval session, ensuring strict continuity and transparency between drafts, and treating author diversity of perspectives as an asset. The process of coproducing a portion of the IPCC with governments is what lends the IPCC its credibility as a voice that is of scientists, but with more weight for policy. Calls for insulation from politics risk undermining the relevance of the SPM. [1]: pending:yes [2]: /embed/graphic-2.gif

There is a fairly broad consensus among both the philosophers who write about climate change and the majority of the climate-policy community that efforts to reduce greenhouse-gas emissions—“mitigation” in the jargon—should not harm the ability of poor countries to grow economically and to reduce as rapidly as possible the widespread poverty their citizens suffer. Indeed, this principle of a “right to development” has been substantially embraced in the United Nations Framework Convention on Climate Change (UNFCCC) itself. Yet as the evidence of the risks from climate change has continued to mount and calls have grown for more stringent mitigation targets, the need to give substance to this right has come into conflict with the evident unwillingness of already “developed” countries to pay the costs of adequately precautionary mitigation. The long and the short of it is that almost any reasonable ethical principles lead to the conclusion that, as Henry Shue (1999) put it straightforwardly, “the costs [of mitigation] should initially be borne by the wealthy industrialized states.” In the words of the UNFCCC, “the developed country Parties should take the lead in combating climate change and the adverse effects thereof,” and this point is embodied in practical terms in the Kyoto Protocol itself, in which only the 40 developed “Annex I” countries have binding emissions limits. Yet particularly because of the rejection of Kyoto by the United States but also because of the weak efforts at mitigation that have taken place so far in Europe, Japan, and other industrialized countries, we find ourselves in a situation in which precaution requires that emissions be reduced extremely soon in poor countries, too, but the rich countries can’t yet be said to have fulfilled their obligations to “take the lead.” The delay in taking action so far, the increasing evidence of current climate-change impacts and greater risks than previously estimated, and the speed with which we must now move all imply substantially greater costs for adequately precautionary action than were previously estimated.

We've been studying the ``tweed'' precursors above the martensitic transition in shape--memory alloys. These characteristic cross--hatched modulations occur for hundreds of degrees above the first--order shape--changing transition. Our two--dimensional model for this transition, in the limit of infinite elastic anisotropy, can be mapped onto a spin--glass Hamiltonian in a random field. We suggest that the tweed precursors are a direct analogy of the spin--glass phase. The tweed is intermediate between the high--temperature cubic phase and the low--temperature martensitic phase in the same way as the spin--glass phase can be intermediate between ferromagnet and antiferromagnet., Comment: 18 pages and four figures (included)

International climate policy is at a crossroads. On the one hand negotiations have reached a deadlock in the past two years as all countries wait for Russia to ratify the Kyoto Protocol. On the other hand there is a lively debate beyond official negotiations on options for the mid- and long-term development of the climate regime, and a growing recognition that such a development is of utmost importance. In the near future, progressive forces in the climate arena should strongly focus on bringing the Kyoto Protocol into force; in the years to come, the crucial issue will be how to design the climate regime so that it effectively combats further climate change without jeopardizing the basic development needs of developing countries. Regardless of when or whether the Kyoto Protocol enters into force, the challenge of future climate negotiations will be to embed the next steps in a long-term framework that aims at an adequate and equitable global climate agreement that takes into account the right to sustainable development of all countries.

Hysteresis loops in some magnetic systems are composed of small avalanches (manifesting themselves as Barkhausen pulses). Hysteresis loops in other first‐order phase transitions (including some magnetic systems) often occur via one large avalanche. The transition between these two limiting cases is studied, by varying the disorder in the zero‐temperature random‐field Ising model. Sweeping the external field through zero at weak disorder, we get one large avalanche with small precursors and aftershocks. At strong disorder, we get a distribution of small avalanches (small Barkhausen effect). At the critical value of disorder where a macroscopic jump in the magnetization first occurs, universal power‐law behavior of the magnetization and of the distribution of (Barkhausen) avalanches is found. This transition is studied by mean‐field theory, perturbative expansions, and numerical simulation in three dimensions.

We use the zero-temperature random-field Ising model to study hysteretic behavior at first-order phase transitions. Sweeping the external field through zero, the model exhibits hysteresis, the return-point memory effect, and avalanche fluctuations. There is a critical value of disorder at which a jump in the magnetization (corresponding to an infinite avalanche) first occurs. We study the universal behavior at this critical point using mean-field theory, and also present preliminary results of numerical simulations in three dimensions., Comment: 12 pages plus 2 appended figures, plain TeX, CU-MSC-7479